Multi-speed power transmissions provide automatic ratio interchanges to accomplish efficient use of an internal combustion engine. The internal combustion engine has an operating speed range and torque range which limit its direct use in many vehicles. The multi-speed transmission extend the usefulness of the engine by reusing a portion to the engine output. The transmission provides many speed ratios such that high torque and low speed output range is available at vehicle launch and high speed lower torque output range is available for highway performance. The overall efficiency of the vehicle is improved by the proper interchange of transmission ratios while the vehicle speed is increased from launch to cruising.
Many signals are required to determine the proper shift sequence and other operating functions in the transmission. Engine throttle position, vehicle speed, engine speed and vehicle acceleration are some of the signals that are utilized. Of these signals, only vehicle acceleration is calculated from other available signals. The common method of determining acceleration is to measure the time it takes for a predetermined number of teeth on a rotating gear to pass and calculate the speed. Then, repeat the measurement for a new set of predetermined number of teeth and calculate a new speed. If the measured speeds differ, the component is accelerating and the value is calculated from the successive speeds.